Skip to content
Commit cf77ee54 authored by Hong H. Pham's avatar Hong H. Pham Committed by Benjamin Herrenschmidt
Browse files

powerpc: Fix PTE page address mismatch in pgtable ctor/dtor



In pte_alloc_one(), pgtable_page_ctor() is passed an address that has
not been converted by page_address() to the newly allocated PTE page.

When the PTE is freed, __pte_free_tlb() calls pgtable_page_dtor()
with an address to the PTE page that has been converted by page_address().
The mismatch in the PTE's page address causes pgtable_page_dtor() to access
invalid memory, so resources for that PTE (such as the page lock) is not
properly cleaned up.

On PPC32, only SMP kernels are affected.

On PPC64, only SMP kernels with 4K page size are affected.

This bug was introduced by commit d614bb04
"powerpc: Move the pte free routines from common header".

On a preempt-rt kernel, a spinlock is dynamically allocated for each
PTE in pgtable_page_ctor().  When the PTE is freed, calling
pgtable_page_dtor() with a mismatched page address causes a memory leak,
as the pointer to the PTE's spinlock is bogus.

On mainline, there isn't any immediately obvious symptoms, but the
problem still exists here.

Fixes: d614bb04 "powerpc: Move the pte free routes from common header"
Cc: Paul Mackerras <paulus@samba.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linux-stable <stable@vger.kernel.org> # v3.10+
Signed-off-by: default avatarHong H. Pham <hong.pham@windriver.com>
Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 1b429835
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment